System, method, and computer-readable medium for mobile-to-mobile calls within femtocell network

ABSTRACT

A system, method, and computer readable medium for terminating calls in a network system is provided. The communication system features an IP-based femtocell system for provisioning communication services to a user equipment. The femtocell system is provisioned with a list of electronic serial numbers of user equipments that are authorized to access the femtocell system. When a call is received by the femtocell system, the femtocell system determines a directory number of a user equipment to which the call is directed. If the destination user equipment is authorized to access the femtocell system and is currently within the service area of the femtocell system, the call setup may be completed by the femtocell system without any call setup signaling being transmitted to a core telecommunication network.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims priority to U.S. provisional patent applicationSer. No. 61/003,151 entitled SIP-IOS ADAPTER FUNCTION filed Nov. 15,2007, the disclosure of each of which is incorporated in its entiretyherein by reference.

FIELD OF THE INVENTION

The present invention is generally related to radio access technologiesand, more particularly, to mechanisms for call termination within anetwork system.

BACKGROUND OF THE INVENTION

Contemporary cellular radio systems, or mobile telecommunicationsystems, provide an over-the-air interface to wireless user equipments(UEs) via a radio access network (RAN) that interfaces with at least onecore network. The RAN may be implemented as, for example, a CDMA2000RAN, a Universal Mobile Telecommunications System (UMTS) RAN, a GlobalSystem for Mobile communications (GSM) RAN, or another suitable radioaccess network implementation. A UE may comprise, for example, a mobileterminal such as a mobile telephone, a laptop computer featuring mobiletelephony software and hardware, a personal digital assistant (PDA), orother suitable equipment adapted to transfer and receive voice or datacommunications with the radio access network.

A RAN covers a geographical area comprised of any number of cells eachcomprising a relatively small geographic area of radio coverage. Eachcell is provisioned by a cell site that includes a radio tower, e.g., abase transceiver station (BTS), and associated equipment. BTSscommunicate with UEs over an air interface within radio range of theBTSs.

Numerous BTSs in the RAN may be communicatively coupled to a basestation controller, also commonly referred to as a radio networkcontroller (RNC). The BSC manages and monitors various system activitiesof the BTSs serviced thereby. BSCs are coupled with at least one corenetwork.

BTSs are typically deployed by a carrier network in areas having a highpopulation density. The traffic capacity of a cell site is limited bythe site's capacity and affects the spacing of cell sites. In suburbanareas, sites are often up to two miles apart, while cell sites deployedin dense urban areas may be as close as one-quarter of a mile apart.Because the traffic capacity of a cell site is finitely limited, as isthe available frequency spectrum, mobile operators have a vestedinterest in technologies that allow for increased subscriber capacity.

A microcell site comprises a cell in a mobile phone network that coversa limited geographic area, such as a shopping center, hotel, airport, orother infrastructure that may have a high density mobile phone usage. Amicrocell typically uses power control to limit the radius of themicrocell coverage. Typically a microcell is less than a mile wide.

Although microcells are effective for adding network capacity in areaswith high mobile telephone usage, microcells extensively rely on theRAN, e.g., a controlling BSC and other carrier functions. Becausecontemporary BSCs have limited processing and interface capacity, thenumber of BTSs—whether microcell BTSs or typical carrier BTSs—able to besupported by the BSC or other RAN functions is disadvantageouslylimited.

Contemporary interest exists in providing small office/home office(SOHO) radio access by an even smaller scale BTS. The radio coveragearea of such a system is typically referred to as a femtocell. In asystem featuring a femtocell, a UE may be authorized to operate in thefemtocell when proximate the femtocell system, e.g., while the UE islocated in the SOHO. When the UE moves beyond the coverage area of thefemtocell, the UE may then be serviced by the carrier network. Theadvantages of deployment of femtocells are numerous. For instance,mobile users frequently spend large amounts of time located at, forexample, home, and many such users rely extensively on cellular networkservice for telecommunication services during these times. For example,a recent survey indicated that nearly thirteen percent of U.S. cellphone customers do not have a landline telephone and rely solely on cellphones for receiving telephone service. From a carrier perspective, itwould be advantageous to have telephone services provisioned over afemtocell system, e.g., deployed in the user's home, to thereby reducethe load, and effectively increase the capacity, on the carrier RANinfrastructure. However, various issues related to maximizing theutilization of femtocell systems remain to be addressed.

Therefore, what is needed is a mechanism that overcomes the describedproblems and limitations.

SUMMARY OF THE INVENTION

The present invention provides a system, method, and computer readablemedium for terminating calls in a network system. The communicationsystem features an IP-based femtocell system for provisioningcommunication services to a user equipment. A femtocell system isprovisioned with a list of electronic serial numbers of user equipmentsthat are authorized to access the femtocell system. When a call isreceived by the femtocell system, the femtocell system determines adirectory number of a user equipment to which the call is directed. Anevaluation may then be performed to determine whether the user equipmentto which the call is directed is authorized to access the femtocellsystem. If the destination user equipment is authorized to access thefemtocell system and is currently within the service area of thefemtocell system, or alternatively in a service area of a femtocellnetwork that includes the femtocell system, the call setup may becompleted by the femtocell system, or the femtocell network, without anycall setup signaling being transmitted to a core telecommunicationnetwork.

In one embodiment of the disclosure, a method for terminating calls in anetwork system is provided. The method includes provisioning a femtocellsystem with a list that specifies at least one electronic serial numberof a user equipment authorized to access the femtocell system, receivinga call setup request by the femtocell system from a first userequipment, determining a directory number of a second user equipment towhich the call is directed, performing an evaluation of whether thesecond user equipment is authorized to access the femtocell system, andcompleting the call setup based on results of the evaluation.

In a further embodiment of the disclosure, a computer-readable mediumhaving computer-executable instructions for execution by a processingsystem, the computer-executable instructions for terminating calls in anetwork system, is provided. The computer-readable medium comprisinginstructions for provisioning a femtocell system with a list thatspecifies at least one electronic serial number of a user equipmentauthorized to access the femtocell system, wherein the list associates adirectory number with a respective one of the at least one electronicserial number, receiving a call setup request by the femtocell systemfrom a first user equipment, determining a directory number of a seconduser equipment to which the call is directed, performing an evaluationof whether the second user equipment is authorized to access thefemtocell system, and completing the call setup based on results of theevaluation.

In a further embodiment of the disclosure, a system for terminatingcalls in a network system is provided. The system includes apacket-switched network, an Internet Protocol multimedia subsystemcommunicatively interfaced with the packet-switched network, and afemtocell system communicatively coupled with the packet-switchednetwork. The femtocell system is adapted to provide a radio interfacewith a user equipment and is provisioned with a list that specifies atleast one electronic serial number of a user equipment authorized toaccess the femtocell system. The list associates a directory number witha respective one of the at least one electronic serial number. Thefemtocell system receives a call setup request from a first userequipment, determines a directory number of a second user equipment towhich the call is directed, performs an evaluation of whether the seconduser equipment is authorized to access the femtocell system, andcompletes the call setup based on results of the evaluation

BRIEF DESCRIPTION OF THE DRAWINGS

Aspects of the present disclosure are best understood from the followingdetailed description when read with the accompanying figures, in which:

FIG. 1 is a diagrammatic representation of a network system thatincludes a cellular network adapted to provide macro-cellular coverage;

FIG. 2 is a diagrammatic representation of a conventional network systemconfiguration featuring a femtocell;

FIG. 3 is a diagrammatic representation of a network system in which afemtocell system implemented in accordance with an embodiment of thepresent invention may be deployed;

FIG. 4 is a simplified diagrammatic representation of the femtocellsystem depicted in FIG. 3 that may be connected with an IP backhaul inaccordance with an embodiment;

FIG. 5 is a diagrammatic representation of an exemplary sessioninitiation protocol registration message generated by a femtocell systemon behalf of a user equipment in accordance with an embodiment;

FIG. 6 is a diagrammatic representation of a network system featuring afemtocell network implemented in accordance with an embodiment;

FIG. 7 is a diagrammatic representation of an electronic serial numberlist that facilitates service screening and mobile-to-mobile callswithin a femtocell network in accordance with an embodiment;

FIG. 8 is a diagrammatic representation of an exemplary softwareconfiguration of a user equipment adapted for engaging in communicationswith femtocell systems in accordance with an embodiment; and

FIG. 9 is a flowchart of a femtocell system call setup routineimplemented in accordance with an embodiment.

DETAILED DESCRIPTION OF THE INVENTION

It is to be understood that the following disclosure provides manydifferent embodiments or examples for implementing different features ofvarious embodiments. Specific examples of components and arrangementsare described below to simplify the present disclosure. These are, ofcourse, merely examples and are not intended to be limiting.

FIG. 1 is a diagrammatic representation of a network system 100 thatincludes a cellular network 110 adapted to provide macro-cellularcoverage to a user equipment. Cellular network 110 may comprise, forexample, a code-division multiple access (CDMA) network, such as aCDMA-2000 network.

Cellular network 110 may include any number of base transceiver stations(BTSS) 112 a-112 c communicatively coupled with a base stationcontroller (BSC) 114 or RNC. Each individual BTS 112 a-112 c under thecontrol of a given BSC may define a radio cell operating on a set ofradio channels thereby providing service to a user equipment (UE) 125,such as a mobile terminal. BSC 114 manages the allocation of radiochannels, receives measurements from mobile terminals, controlshandovers, as well as various other functions as is understood. BSC 114is interconnected with a mobile services switching center (MSC) 116 thatprovides mobile terminal exchange services. BSC 114 may be additionallycoupled with a packet data serving node (PDSN) 118 or other gatewayservice that provides a connection point between the CDMA radio accessnetwork and a packet network, such as Internet 160, and providesmobility management functions and packet routing services. MSC 116 maycommunicatively interface with a circuit switched network, such as thepublic switched telephone network (PSTN) 150, and may additionally becommunicatively coupled with an interworking function (IWF) 122 thatprovides an interface between cellular network 110 and PSTN 150.

System 100 may also include a signaling system, such as a signalingsystem #7 (SS7) network 170. SS7 network 170 provides a set of telephonysignaling protocols which are used to set up the vast majority of theworld's PSTN telephone calls. SS7 network 170 is also used in cellularnetworks for circuit switched voice and packet-switched dataapplications. As is understood, SS7 network 170 includes varioussignaling nodes, such as any number of service control points (SCPs)172, signal transfer points (STPs) 174, and service switching points(SSPs) 176.

BTSs 112 a-112 c deployed in cellular network 110 may service numerousnetwork 110 subscribers. Cell cites provided by BTSs 112 a-112 ccommonly feature site ranges of a quarter to a half mile, e.g., indensely populated urban areas, to one to two miles in suburban areas. Inother remotely populated regions with suitable geography, site rangesmay span tens of miles and may be effectively limited in size by thelimited transmission distance of relatively low-powered UEs. As referredto herein, a cell provided by a BTS deployed in carrier network 110 foraccess by any authorized network 110 subscriber is referred to as amacrocell.

FIG. 2 is a diagrammatic representation of a conventional network system200 configuration featuring a femtocell. In the depicted example, acentral BSC 214 deployed in a cellular carrier network 210 may connectwith a soft switch core 212 that is connected with a MSC 216. MSC 216connects with the cellular core network and may interface with othernetworks, such as the PSTN as is understood. BSC 214 may be connectedwith and service numerous BTSs 212 a-212 c that provide macrocells tocellular network 210 subscribers.

BSC 214 may additionally connect with a tunnel gateway system 218 thatis adapted to establish secured tunnels 232 a-232 x with respectivefemtocell systems 250 a-250 x. Femtocells comprise cellular accesspoints that connect to a mobile operator's network using, for example, aresidential DSL or cable broadband connection. Femtocells 250 a-250 xprovide a radio access point for UE 225 when the UE is within range of afemtocell system with which the UE has authorized access. For example,femtocell system 250 a may be deployed in a residence of the user of UE225. Accordingly, when the user is within the residence, mobiletelecommunications may be provided to UE 225 via an air-interfaceprovided by femtocell system 250 a. In this instance, UE 225 iseffectively offloaded from the macro BTS, e.g., BTS 212 a, andcommunications to and from the UE are carried out with femtocell system250 a over Internet 260. Thus, femtocell systems 250 a-250 x may reducethe radio resource demands by offloading UEs from macrocells tofemtocells and thereby provide for increased subscriber capacity ofcellular network 210.

In contemporary implementations such as that depicted in FIG. 2, afemtocell system 250 a comprises a transceiver without intelligence andis thus required to be connected and managed by BSC 214. Thus, femtocellsystems 250 a-250 x are reliant on the carrier network centralized BSC214 which has limited capacity and thus does not exhibit desirablescaling characteristics or capabilities. Moreover, high communicationsoverhead are realized by the BTS backhaul.

FIG. 3 is a diagrammatic representation of a network system 300 in whicha femtocell system implemented in accordance with an embodiment of theinvention may be deployed. System 300 includes a radio access network(RAN) 310 that provides an over-the-air interface with a UE 325, e.g., amobile terminal. RAN 310 may comprise, for example, a CDMA radio accessnetwork or another suitable RAN. RAN 310 may comprise various BTSs andassociated base station controllers BSCs as well as other infrastructureas is understood. UE 325 may be implemented as a personal digitalassistant (PDA), a mobile phone, a computer, or another device adaptedto interface with RAN 310.

System 300 may include an IP Multimedia Subsystem (IMS) 320 architectureadapted to provide IP service to UE 325. To this end, RAN 310 iscommunicatively coupled with a serving general packet radio service(GPRS) support node (SGSN) 314 and a gateway GPRS support node (GGSN)316. SGSN 314 provides the delivery of data packets from and to UE 325within its service area. GGSN 316 provides an interface between the GPRSbackbone network and external packet data networks. GGSN 316 iscommunicatively coupled with a policy decision function (PDF) 318 thatprovides authorization of media plane resources, e.g., quality ofservice (QoS) authorizations, policy control, bandwidth management, andthe like. PDF 318 may be communicatively coupled with a call sessioncontrol function (CSCF) 320.

CSCF 320 comprises various session initiation protocol (SIP) servers orproxies that process SIP signaling packets in IMS 320. CSCF 320 mayinclude a proxy-CSCF (P-CSCF) that provides a first point of contact foran IMS-compliant UE. The P-CSCF may be located in the visited network,or in the UE's home network if the visited network is not fullyIMS-compliant. UE 325 may discover the P-CSCF, e.g., by using DynamicHost Configuration Protocol (DHCP), or by assignment in a packet dataprotocol (PDP) context. CSCF 320 additionally includes a Serving-CSCF(S-CSCF) that comprises the central node of the signaling plane. TheS-CSCF comprises a SIP server, but additionally performs sessioncontrol. The S-CSCF is located in the home network and interfaces with ahome subscriber server (HSS) 340 to download and upload user profiles.CSCF 320 further includes an Interrogating-CSCF (I-CSCF) that comprisesa SIP function located at the edge of an administrative domain. TheI-CSCF has an IP address that is published in the Domain Name System(DNS) 372 that facilitates location of the I-CSCF by remote servers.Thus, the I-CSCF is used as a forwarding point for receipt of SIPpackets within the domain.

HSS 340 comprises a user database that supports the IMS network entitiesthat manage calls. HSS 340 stores user profiles that specifysubscription-related information of authorized users, authenticates andauthorizes users, and provides information about the user's physicallocation. Various application servers (AS) 342 a-342 n that host andexecute services interface with CSCF 320 via SIP.

CSCF 320 is coupled with a breakout gateway control function (BGCF) 322that comprises a SIP server that provides routing functionality based ontelephone numbers. BGCF 322 is used when a UE places a call from the IMSto a phone in a circuit switched network, e.g., PSTN 330, or the publicland mobile network. A media gateway controller Function (MGCF) 324performs call control protocol conversion between SIP and ISDN User Part(ISUP) and interfaces with a signaling gateway (SGW) 326. SGW 326interfaces with the signaling plane of a circuit switched network, e.g.,PSTN 330. SGW 326 may transform lower layer protocols, such as StreamControl Transmission Protocol (SCTP), into the Message Transfer Part(MTP) protocol, and pass ISUP data from MGCF 324 to PSTN 330 or anothercircuit switched network. A media gateway (MGW) 328 interfaces with themedia plane of PSTN 330 or another circuit switched network byconverting data between real-time transport protocol (RTP) and pulsecode modulation (PCM), and may also be employed for transcoding when thecodecs of the IMS and circuit switched networks differ. Resources of MGW328 are controlled by MGCF 324. Fixed access, e.g., IP telephony devices374 a-374 b, may connect with IMS network via Internet 370 that iscommunicatively coupled with IMS network 320 by way of border gateway360.

As is understood, DNS 372 comprises a scalable namespace thatfacilitates access to entities deployed on the Internet or privatenetworks. DNS 372 maintains various records for host names, servers, andthe like. For example, DNS 372 maintains records (commonly referred toas “A records”) that map hostnames to IP addresses, pointer (PTR)records that map IP addresses to canonical names to facilitate reverseDNS lookups, service (SRV) records that specify information on availableservices, naming authority pointer (NAPTR) records that facilitateregular expression based rewriting, and various other records. DNS 372may additionally include a telephone number mapping (ENUM) system thatfacilitates resolution of SIP addresses from E.164 number as isunderstood.

A base station manager (BSM) 378 may be deployed in Internet 370 and maybe adapted to communicate with numerous femtocell systems and femtocellnetworks. BSM 378 may provide various operations, maintenance, andmanagement functions to femtocell systems. For example, BSM 378 mayprovide service provisioning of femtocell systems, e.g., by providingconfiguration downloads to femtocell systems and preloading defaultconfiguration data for femtocell systems distributed via sales channels.BSM 378 may provide various support and maintenance features, such asalarm and periodic statistics reporting, automatic remote software imagedistribution to femtocell systems, provide upgrades andreconfigurations, and may provide remote access via Internet 370 fordiagnostics and customer support.

In accordance with an embodiment, a femtocell system 350 may includeintegrated BTS and BSC functions and may feature additional capabilitiesavailable in the provided femtocell site coverage area. Femtocell system350 provides an IP-accessible radio access network, is adapted foroperation with IMS 320, and provides radio link control functions.Femtocell system 350 may be communicatively coupled with Internet 370via any variety of backhaul technologies, such as an 802.11x link, a10/100 BaseT LAN link, a T1/E1 Span or fiber, cable set top box, DSLmodem connected with a central office digital subscriber line accessmultiplexer, a very small aperture terminal (VSAT), or another suitablebackhaul infrastructure.

In an embodiment, femtocell system 350 includes a session initiationprotocol (SIP) adapter that supports a SIP client pool and providesconversion of call set-up functions to SIP client set-up functions. Forexample, a SIP client pool allocated by femtocell system 350 maycomprise a plurality of SIP user agents 352 a-352 c that each may beallocated for a UE authorized to access femtocell system 350.Additionally, femtocell system 350 includes electronic serial number(ESN) screening to allow only designated UEs to access the femtocellthereby restricting access to authorized home or small office UEs. Forexample, femtocell system 350 may be configured with an ESN list 354that specifies ESNs of UEs authorized to access femtocell system 350. Inthe illustrative example, ESNs of “ESN 1”-“ESN 3” are included in ESNlist 354. Provisioning of ESN(s) may be made as part of an initialfemtocell system 350 activation. In the illustrative example, femtocellsystem 350 is allocated an Internet Protocol (IP) address of“66.249.73.42”, and UE 325 is allocated a mobile services ISDN (MSISDN)number, or E.164 number, of “12145551212”.

FIG. 4 is a simplified diagrammatic representation of femtocell system350 depicted in FIG. 3 that facilitates provisioning of a femto-RAN inaccordance with an embodiment. Femtocell system 350 includes an antenna400 coupled with a BTS 410. BTS 410 may be implemented, for example, asa 1xRTT ASIC device and may comprise a non-diversity receiver featuringa built-in duplexer. In an embodiment, BTS 410 may feature only oneoperational band and may include a transmitter scan receiver and localoscillator. BTS 410 may be communicatively coupled with a BSC 420 thatprovides radio control functions, such as receiving measurements fromUEs, such as mobile phones, control of handovers to and from otherfemtocell systems, and may additionally facilitate handoff to or frommacrocells.

Femtocell system 350 includes an electronic serial number screeningfunction 430 that may facilitate approving or rejecting service for a UEby femtocell system 350. Additionally femtocell system 350 includes anInternet Operating System (IOS) and SIP Adapter (collectively referredto as IOS-SIP Adapter 440). IOS-SIP adapter 440 may invoke and manageSIP clients, such as a user agent (UA) pool comprising one or more UAs.In accordance with an embodiment, each UE 325 authorized to be servicedby femtocell system 350 may have a UA allocated therefor by femtocellsystem in a manner that facilitates transmission of communications toand from a UE over an IP backhaul. Accordingly, when an authorized UE iswithin the femtocell system 350 site range, telecommunication servicesmay be provided to the UE via the IP backhaul and femtocell system 350provisioned RAN. When the UE is moved beyond the service range offemtocell system 350, telecommunication service may then be provided tothe UE via macrocellular coverage.

To facilitate routing of calls from circuit switched call originators,femtocell system 350 may perform a DNS/ENUM registration on behalf ofUEs authorized to obtain service from femtocell system 350. In thepresent example, assume UE 325 with a MSISDN of “12145551212” has a SIPservice subscription in the domain “example.com” and has a SIP uniformresource identifier (URI) of “12145551212@example.com”. An exampleDNS/ENUM registration message generated by femtocell system 350 onbehalf of UE 325 and transmitted to DNS 372 is as follows:

$ORIGIN 2.1.2.1.5.5.5.4.1.2.1.e164.arpa. IN NAPTR 100 10 “u” “E2U+sip”“!{circumflex over ( )}.*$!sip:12145551212@example.com!”.

As is understood, the first line of the registration message comprisesthe MSISDN number of the UE converted (i.e., reversed with each numeraldelineated with a “.” character and appended with the e164.arpa domain)for DNS lookup. The second line of the registration message specifiesthe NAPTR record for the hosts that can further process the address—thedomain “example.com” (in which the UE with a URI of12145551212@example.com is registered) in the present example.

Femtocell system 350 may generate and issue a SIP registration on behalfof UE 325 authorized for service access by femtocell system 350. FIG. 5is a diagrammatic representation of an exemplary SIP registrationmessage 500 generated by femtocell system 350 on behalf of UE 325authorized for service access thereby in accordance with an embodiment.Registration message 500 may be transmitted from femtocell system 350 toa location service, such as a SIP registrar implemented as SIP Registrar380. Registrar 380 may provide the location and contact information tolocation service 382. Registration message 500 includes a REGISTER field510 that specifies the registration is being made within the domain“example.com”. In accordance with an embodiment, multiple contacts areincluded in registration message 500. In the present example,registration message 500 includes a contact field 512 that specifies aSIP contact for UE 325. Notably, the SIP contact field 512 for UE 325specifies the UA registered on behalf of UE with the URI12145551212@example.com is located at the IP address of “66.249.73.42”.That is, the SIP contact registered by femtocell system 350 on behalf ofUE 325 is to be addressed at the femtocell system 350 address of66.249.73.42 thereby resulting in routing of SIP signaling messages tofemtocell system 325. In turn, femtocell system 350 may convert SIP callset up messaging to RAN signaling, allocate an uplink and a downlinkchannel for UE 325, and set up a call or data session thereon.

In the present example, registration message 500 includes a secondcontact field 514 that specifies a telephone URI, e.g., the MSISDN+1-214-555-1212 of UE 325. Thus, a location query for the SIP URIsip:12145551212@example.com would return two contacts. The first is theSIP URI that can be used to reach femtocell system 350, and thus UE 325thereby, and the second is the telephone URI that can be used to reachUE 325 via macrocellular coverage, i.e., via RAN 310. As is understood,the order of contacts 512-514 provides a contact preference, and themultiple contacts may be registered in separate registration messages.The depicted registration message including both the SIP contact URI andtelephone URI is exemplary only. Accordingly, in the present example, anattempt to contact UE 325 may first be made via the SIP URI12145551212@example.com. In the event that the session is notsuccessfully set up via the SIP contact, an attempt may be made to setupa session via RAN 310 using the telephone URI.

When the UE 325 moves outside the coverage area of femtocell system 350,another registration may be generated and submitted by femtocell system350 on behalf of UE 325 where the telephone URI is designated as thepreferred contact. Further, the SIP URI may be removed from theregistration when the UE 325 moves outside the coverage area offemtocell system 350 thereby avoiding any attempts to establish asession with UE 325 via femtocell system 350 when UE 325 has movedbeyond the femtocell system 350 coverage area.

In accordance with an embodiment, a network of femtocell systems may bedeployed and connected with an IP backhaul. In this implementation, anauthorized UE may be serviced by the femtocell network, and service maybe transferred from one femtocell to another femtocell via a femtocellhandoff procedure. In the event that the femtocell network is deployedin an area serviced by a macrocellular network, handoff routines mayprovide preference for transferring a UE to a target femtocell systemrather than a macrocell site. In the event that a suitable femtocell isunavailable for handoff of a UE, the UE may be transferred to themacrocell site.

FIG. 6 is a diagrammatic representation of a network system 600featuring a femtocell network implemented in accordance with anembodiment of the invention. System 600 includes a RAN 610 that providesan over-the-air interface with one or more UEs 625 a-625 c, e.g., amobile terminal. RAN 610 may comprise, for example, a CDMA radio accessnetwork or another suitable RAN. RAN 610 may comprise various BTSs 612a-612 c and associated BSCs 604 as well as other infrastructure as isunderstood. Each of BTSs 612 a-612 c provide a respective macrocell 602a-602 c that may provide telecommunication service to UEs 625 a-625 c.BSC 604 is coupled with a MSC 606 that provides cellular exchangeservices, mobility management, and other services within the area thatit serves as is understood.

RAN 610 may interface with IMS 620 adapted to provide IP service to UEs625 a-625 c. To this end, RAN 610 may be communicatively coupled with aSGSN 614 and a GGSN 616. GGSN 616 is communicatively coupled with a PDF618 that provides authorization of media plane resources. PDF 618 may becommunicatively coupled with a CSCF 620.

CSCF 620 comprises various SIP servers or proxies that process SIPsignaling packets in IMS 620. CSCF 620 may include a P-CSCF, a S-CSCF,and an I-CSCF as is understood. HSS 640 stores user profiles thatspecify subscription-related information of authorized users,authenticates and authorizes users, and provides information about theuser's physical location. Various application servers 642 a-642 n mayhost and execute services and is interfaced with CSCF 620 via SIP.

The I-CSCF has an IP address that is published in DNS 672 thatfacilitates location of the I-CSCF by remote servers. Thus, the I-CSCFis used as a forwarding point for receipt of SIP packets within thedomain.

CSCF 620 is coupled with a BGCF 622 that comprises a SIP server thatprovides routing functionality based on telephone numbers. A MGCF 624performs call control protocol conversion between SIP and ISDN User Part(ISUP) and interfaces with a SGW 626 that itself interfaces with thesignaling plane of a circuit switched network, e.g., PSTN 630. A MGW 628interfaces with the media plane of PSTN 630 or another circuit switchednetwork. Resources of MGW 628 are controlled by MGCF 624. Fixed accessdevices, e.g., IP telephony devices 674 a-674 b, may connect with IMSnetwork via Internet 670 that is communicatively coupled with IMSnetwork 620 by way of border gateway 660.

A BSM 678 may be deployed in Internet 670 and may be adapted tocommunicate with numerous femtocell systems and femtocell networks. BSM678 may provide various operations, maintenance, and managementfunctions to femtocell systems. BSM 678 may provide service provisioningof femtocell systems, e.g., by providing configuration downloads tofemtocell systems and preloading default configuration data forfemtocell systems distributed via sales channels. BSM 678 may providevarious support and maintenance features, such as alarm and periodicstatistics reporting, automatic remote software image distribution tofemtocell systems, provide upgrades and reconfigurations, and mayprovide remote access via Internet 670 for diagnostics and customersupport.

Femtocell systems 650 a-650 c may include integrated BTS and BSCfunctions and may feature additional capabilities available in theprovided femtocell site coverage areas. Femtocell systems 650 a-650 cprovide an IP-accessible radio access network, are adapted for operationwith IMS 620, and provide radio link control functions. Femtocellsystems 650 a-650 c may be communicatively coupled with Internet 670 viaany variety of backhaul technologies, such as an 802.11x link, a 10/100BaseT LAN link, a T1/E1 Span or fiber, cable set top box, DSL modemconnected with a central office digital subscriber line accessmultiplexer, a very small aperture terminal (VSAT), or another suitablebackhaul infrastructure. In the illustrative example, femtocell systems650 a-650 c are each coupled with an IP backhaul access device 655, suchas an Ethernet cable or DSL router. For instance, femtocell systems 650a-650 c may be coupled with access node 655 via respective 10/100BaseTtwisted pair cables, Category 5 cabling, or other suitableinterconnection.

Each of femtocell systems 650 a-650 c provide a respective femtocellsite 651 a-651 c in which UEs 625 a-625 c may be providedtelecommunication services over an air interface. Femtocell systems 650a-650 c are communicatively coupled with one another via access device655. Femtocell systems 650 a-650 c deployed for conjunctively providinga femtocell service coverage area comprised of the collective femtocellsites 651 a-651 c are collectively referred to herein as a femtocellnetwork. In an embodiment, femtocell systems 650 a-650 c may exchangemessages with one another to facilitate handoff of a UE from onefemtocell to another, e.g., as UE 625 a moves out of the radio range ofa femtocell and into the radio range of another. In the depictedexample, the femtocell network provided by femtocell systems 650 a-650 cis at least partially overlapped by one or more macrocell sites 602a-602 c provisioned by macrocell BTSs 612 a-612 c. In such animplementation, femtocell systems 650 a-650 c may provide preference toanother femtocell for handoff of a UE thereto. In the event that anotherfemtocell is not available or is unsuitable for a handoff, the UE maythen be transferred to macrocellular coverage via a handoff to amacrocell BTS.

Each of femtocell system 650 a-650 c may include a respective SIPadapter that supports a SIP client pool and provides conversion of callset-up functions to SIP client set-up functions. Additionally, femtocellsystems 650 a-650 c include ESN screening to allow only designated UEsto access the femtocells thereby restricting access to authorized homeor small office UEs. For example, femtocell system 650 a may beconfigured with an ESN list 654 a that specifies ESNs of UEs authorizedto access femtocell system 650. In the illustrative example, ESNs of“ESN 1”-“ESN 3” are included in ESN list 654 a. Assume for illustrativepurposes that each of UEs 625 a-625 c are authorized to access thefemtocell network comprising femtocell systems 650 a-650 c and that theESNs “ESN 1”-“ESN 3” are the respective ESNs of UEs 625 a-625 c.Provisioning of ESN(s) may be made as part of an initial femtocellsystem 650 activation. Other femtocell systems 650 b-650 c may besimilarly configured with an ESN list including ESNs of UEs authorizedto access the femtocell system network comprised of femtocell systems650 a-650 c. In the illustrative example, femtocell systems 650 a-650 care allocated a respective IP address of “66.249.73.42”, “66.249.73.43”,and “66.249.73.44”.

FIG. 7 is a diagrammatic representation of an ESN list 700, such as ESNlist 654 a depicted in FIG. 6, that facilitates service screening andmobile-to-mobile calls within a femtocell network in accordance with anembodiment. In the illustrative example, the ESN list is implemented asa table although other data structures may be suitably substitutedtherefor.

ESN list 700 comprises a plurality of records 710 and fields 720 inwhich ESNs and, optionally, associated directory numbers of UEsauthorized to access a femtocell system that maintains ESN list 700 maybe stored. ESN list 700 may be stored on a memory device of a femtocellsystem, fetched therefrom by a processor of the femtocell system, andprocessed thereby.

Fields 720 a-720 b have a respective label, or identifier, thatfacilitates insertion, deletion, querying, or other data operations ormanipulations of ESN list 700. In the illustrative example, fields 720a-720 b have respective labels of “ESN” and “Directory Number”.

In the illustrative example, ESN field 720 a stores ESNs of UEsauthorized to access the femtocell system or femtocell network.Directory Number field 720 b stores directory numbers, e.g., an MSISDN,of the UE having the associated ESN maintained by field 720 a. In thepresent example, records 710 a-710 c specify three UEs are authorized toaccess the femtocell system and have respective ESNs of “ESN 1”-“ESN 3”and respective directory numbers of “12145551212”-“12145551214”. In theexamples provided herein, assume UEs 625 a-625 are authorized to accessthe femtocell network comprising femtocell systems 650 a-650 c andfurther assume that UEs 625 a-625 c respectively have ESNs of “ESN1”-“ESN 3” and respective directory numbers of“12145551212”-“12145551214”. Each of femtocell systems 650 a-650 c maybe configured with an instance of the ESN list depicted in FIG. 7 forscreening service to only authorized UEs and for setting up callsbetween authorized UEs within the femtocell network without placing anyload on the core network as described more fully hereinbelow.

FIG. 8 is a diagrammatic representation of an exemplary softwareconfiguration 800 of a UE, such as UE 625 a, adapted for engaging incommunications with femtocell systems in accordance with an embodiment.In the exemplary configuration of FIG. 8, the UE is configured withaccess network-specific software entities 860, e.g., protocol and driversoftware associated with a particular access network technology, such asCDMA, GSM, UMTS, or another suitable radio access network, and isdependent on the particular cellular and femtocell access technology inwhich the UE is to be deployed. While configuration 800 depicts a UEadapted for deployment in a single access network technology type, theUE may be implemented as a multi-mode device and may accordingly includea plurality of access-specific entities in accordance with anembodiment. The particular configuration 800 is illustrative only and isprovided only to facilitate an understanding of embodiments disclosedherein.

In the illustrative example, configuration 800 includes a cellular modemdriver 802 for providing a physical interface with the access network inwhich the UE is deployed. An access-stratum 804 and a non-access stratum806 may be included in configuration 800. A cellular radio interface 808may be communicatively coupled with lower layers of configuration 800and may additionally interface with network and session managementlayers, e.g., a network stack 810. Configuration 800 may include anoperating system 814, such as Symbian, Blackberry O/S, or anotheroperating system suitable for mobile applications, and may coordinateand provide control of various components within the UE. Configuration800 may include a femto application 812 that facilitates femtocellnetwork acquisition and handoff of a UE from a macrocellular network toa femtocell system and may facilitate handoff between femtocell systemswithin a femtocell network.

Configuration 800 may include a preferred roaming list (PRL) 816 thatcontains information used during the system selection and acquisitionprocess. PRL 816 indicates which bands, sub-bands and service provideridentifiers will be scanned, and the priority of the scan order. In theillustrative example, PRL 816 includes four entries 816 a-816 d thatrespectively specify four networks (illustratively designated “Femto”,“Macro 1”, “Macro 2”, and “Roam 1”). In the present example, assume“Femto” refers to the network of femtocell systems 650 a-650 c. Thefemtocell network is specified first in the prioritized list of PRLentries and thus indicates that the femtocell network is the preferredaccess network. Assume “Macro 1” refers to radio access network 610, and“Macro 2” refers to another cellular network. “Roam 1” specified by PRLentry 816 d may refer to another cellular network that may have aroaming agreement with the UE home network. As is understood, PRL 816may comprise an acquisition table that specifies a list of frequenciesassociated with each of the networks specified in the roaming list onwhich the UE may scan during search of a particular system and mayfurther specify PN offsets thereof. The acquisition table mayadditionally specify a network type of each listed network andassociated channel blocks.

Femtocell systems 650 a-650 c include ESN screening to allow onlydesignated UEs to access the femtocells thereby restricting access toonly authorized home or small office UEs. ESN lists, such as ESN list654 a, specifying ESNs of authorized UEs may be downloaded to femtocellsystems 650 a-650 c, for example from BSM 678. In accordance with anembodiment, mobile-to-mobile calls may be made within a femtocellnetwork between authorized UEs without any loading on the core network.The ESN list may associate ESNs with MSISDN or E.164 numbers, i.e., thedirectory numbers, of UEs. In an embodiment, when a call request is madeby a UE within a femtocell network, the femtocell system with which theUE is registered and that receives the call request may evaluate thedestination number to determine if the destination number is assigned toa UE that has authorization to operate in the femtocell network. In theevent that the destination number corresponds to a UE that hasauthorized femtocell system access, the femtocell system may thendetermine whether the called UE is currently within the service area ofthe femtocell network. If the called UE is currently within thefemtocell network service area, the femtocell system receiving the callrequest may complete the call setup within the femtocell network withoutany signaling being supplied to the IMS core network or themacrocellular network.

FIG. 9 depicts a flowchart 900 of a femtocell system call setup routineimplemented in accordance with an embodiment. The processing steps ofFIG. 9 may be implemented as computer-executable instructions executableby a processing system, such as a femtocell system, in accordance withan embodiment.

The call setup routine is invoked (step 902), and a call request isreceived by a femtocell system (step 904). The femtocell system thenreads the destination directory number from the call setup request (step906). The femtocell system then evaluates whether the destinationdirectory number is assigned to a UE that is authorized to access thefemtocell network (step 908). For example, the femtocell system mayinterrogate the ESN list, e.g., ESN list 700, with the destinationdirectory number of the call setup request and determine if a directorynumber of the ESN list matches the destination number. If thedestination number does not match a directory number of an authorizedUE, the femtocell system may then direct the call setup to the corenetwork for setup of the call (step 910), and the call setup routinecycle may then end (step 916).

Returning again to step 908, if the destination directory number isassigned to an authorized UE, the femtocell system may then evaluatewhether the UE is currently located in the femtocell network servicearea (step 912). For example, the femtocell system receiving the callsetup request may evaluate any authorized UEs currently within thefemtocell system's service area to determine if the destination UE isbeing serviced by the UE. Additionally, the UE may evaluate any UEsbeing serviced by other femtocell systems of the femtocell network todetermine if the destination UE is currently in a service area of anyother femtocell systems of the femtocell network. If the destination UEis not currently located within the service area of the femtocellnetwork, the femtocell system may then direct the call setup to the corenetwork according to step 910. If the destination UE is currentlylocated within the service area of the femtocell network, the call setupmay then be completed within the femtocell network (step 914) withoutany call setup signaling being transmitted on the core network. The callsetup routine cycle may then end according to step 916.

As described, a communication system featuring an IP-based femtocellsystem for provisioning communication services to a user equipment isprovided. In one implementation, a femtocell system is provisioned witha list of electronic serial numbers of user equipments that areauthorized to access the femtocell system. When a call is received bythe femtocell system, the femtocell system determines a directory numberof a user equipment to which the call is directed. An evaluation maythen be performed to determine whether the user equipment to which thecall is directed is authorized to access the femtocell system. If thedestination user equipment is authorized to access the femtocell systemand is currently within the service area of the femtocell system, oralternatively in a service area of a femtocell network that includes thefemtocell system, the call setup may be completed by the femtocellsystem, or the femtocell network, without any call setup signaling beingtransmitted to a core telecommunication network.

The flowchart of FIG. 9 depicts process serialization to facilitate anunderstanding of disclosed embodiments and is not necessarily indicativeof the serialization of the operations being performed. In variousembodiments, the processing steps described in FIG. 9 may be performedin varying order, and one or more depicted steps may be performed inparallel with other steps. Additionally, execution of some processingsteps of FIG. 9 may be excluded without departing from embodimentsdisclosed herein.

The illustrative block diagrams depict process steps or blocks that mayrepresent modules, segments, or portions of code that include one ormore executable instructions for implementing specific logical functionsor steps in the process. Although the particular examples illustratespecific process steps or procedures, many alternative implementationsare possible and may be made by simple design choice. Some process stepsmay be executed in different order from the specific description hereinbased on, for example, considerations of function, purpose, conformanceto standard, legacy structure, user interface design, and the like.

Aspects of the present invention may be implemented in software,hardware, firmware, or a combination thereof. The various elements ofthe system, either individually or in combination, may be implemented asa computer program product tangibly embodied in a machine-readablestorage device for execution by a processing unit. Various steps ofembodiments of the invention may be performed by a computer processorexecuting a program tangibly embodied on a computer-readable medium toperform functions by operating on input and generating output. Thecomputer-readable medium may be, for example, a memory, a transportablemedium such as a compact disk, a floppy disk, or a diskette, such that acomputer program embodying the aspects of the present invention can beloaded onto a computer. The computer program is not limited to anyparticular embodiment, and may, for example, be implemented in anoperating system, application program, foreground or background process,driver, network stack, or any combination thereof, executing on a singleprocessor or multiple processors. Additionally, various steps ofembodiments of the invention may provide one or more data structuresgenerated, produced, received, or otherwise implemented on acomputer-readable medium, such as a memory.

Although embodiments of the present invention have been illustrated inthe accompanied drawings and described in the foregoing description, itwill be understood that the invention is not limited to the embodimentsdisclosed, but is capable of numerous rearrangements, modifications, andsubstitutions without departing from the spirit of the invention as setforth and defined by the following claims. For example, the capabilitiesof the invention can be performed fully and/or partially by one or moreof the blocks, modules, processors or memories. Also, these capabilitiesmay be performed in the current manner or in a distributed manner andon, or via, any device able to provide and/or receive information.Further, although depicted in a particular manner, various modules orblocks may be repositioned without departing from the scope of thecurrent invention. Still further, although depicted in a particularmanner, a greater or lesser number of modules and connections can beutilized with the present invention in order to accomplish the presentinvention, to provide additional known features to the presentinvention, and/or to make the present invention more efficient. Also,the information sent between various modules can be sent between themodules via at least one of a data network, the Internet, an InternetProtocol network, a wireless source, and a wired source and viaplurality of protocols.

1. A method of terminating calls in a network system, comprising:provisioning a femtocell system with a list that specifies at least oneelectronic serial number of a user equipment authorized to access thefemtocell system; receiving a call setup request by the femtocell systemfrom a first user equipment, the call setup comprising a directorynumber of a second user equipment; determining the directory number ofthe second user equipment to which the call is directed; interrogatingthe list with the directory number of the call setup request todetermine if a directory number of the list matches the directory numberof the second user equipment; performing an evaluation of whether thesecond user equipment is authorized to access the femtocell system byevaluating whether the directory number is assigned to the second userequipment that is authorized to access the femtocell system, and byevaluating whether the second user equipment is currently operating in aservice area of the femtocell system; and completing the call setupbased on results of the evaluation.
 2. The method of claim 1, whereinthe list associates a directory number with a respective one of the atleast one electronic serial number.
 3. The method of claim 2, furthercomprising determining an electronic serial number of the second userequipment.
 4. The method of claim 3, wherein determining an electronicserial number further comprises: interrogating the list with thedirectory number; and reading the electronic serial number from thelist, where the electronic serial number is associated with thedirectory number.
 5. The method of claim 1, where performing theevaluation results in determining the second user equipment isauthorized to access the femtocell system.
 6. The method of claim 5,further comprising determining the second user equipment is registeredwith one of the femtocell system and a femtocell network that includesthe femtocell system.
 7. The method of claim 6, where completing thecall setup further comprises completing the call setup with one of thefemtocell system and a femtocell network that includes the femtocellsystem, and where no call setup singling is transmitted outside the atleast one femtocell system and the femtocell network.
 8. The method ofclaim 1, where performing an evaluation results in determining thesecond user equipment is not authorized to access the femtocell system,and where completing the call setup comprises completing the call setupthrough a network core with which the femtocell system iscommunicatively coupled.
 9. A non-transitory computer-readable storagemedium having computer-executable instructions for execution by aprocessing system, the computer-executable instructions for terminatingcalls in a network system, the computer-readable medium comprisinginstructions for: provisioning a femtocell system with a list thatspecifies at least one electronic serial number of a user equipmentauthorized to access the femtocell system, wherein the list associates adirectory number with a respective one of the at least one electronicserial number; receiving a call setup request by the femtocell systemfrom a first user equipment, the call setup comprising a directorynumber of a second user equipment; determining the directory number ofthe second user equipment to which the call is directed; interrogatingthe list with the directory number of the call setup request todetermine if a directory number of the list matches the directory numberof the second user equipment; performing an evaluation of whether thesecond user equipment is authorized to access the femtocell system byevaluating whether the directory number is assigned to the second userequipment that is authorized to access the femtocell system, and byevaluating whether the second user equipment is currently operating in aservice area of the femtocell system; and completing the call setupbased on results of the evaluation.
 10. The non-transitorycomputer-readable storage medium of claim 9, further comprisinginstructions for determining an electronic serial number of the seconduser equipment.
 11. The non-transitory computer-readable storage mediumof claim 10, wherein the instructions for determining an electronicserial number further comprise instructions for: interrogating the listwith the directory number; and reading the electronic serial number fromthe list, wherein the electronic serial number is associated with thedirectory number.
 12. The non-transitory computer-readable storagemedium of claim 9, wherein the instructions for performing theevaluation determine the second user equipment is authorized to accessthe femtocell system.
 13. The non-transitory computer-readable storagemedium of claim 12, further comprising instructions for determining thesecond user equipment is registered with one of the femtocell system anda femtocell network that includes the femtocell system.
 14. Thenon-transitory computer-readable storage medium of claim 13, wherein theinstructions for completing the call setup further comprise instructionsfor completing the call setup with one of the femtocell system and afemtocell network that includes the femtocell system, and wherein nocall setup singling is transmitted outside the at least one femtocellsystem and the femtocell network.
 15. The non-transitorycomputer-readable storage medium of claim 9, wherein the instructionsfor performing an evaluation determine the second user equipment is notauthorized to access the femtocell system, and wherein the instructionsfor completing the call setup comprise instructions for completing thecall setup through a network core with which the femtocell system iscommunicatively coupled.
 16. A system for terminating calls in a networksystem, comprising: a packet-switched network; an Internet Protocolmultimedia subsystem communicatively interfaced with the packet-switchednetwork; and a femtocell system communicatively coupled with thepacket-switched network adapted to provide a radio interface with a userequipment and that is provisioned with a list that specifies at leastone electronic serial number of a user equipment authorized to accessthe femtocell system, wherein the list associates a directory numberwith a respective one of the at least one electronic serial number,wherein the femtocell system receives a call setup request by thefemtocell system from a first user equipment, the call setup comprisinga directory number of a second user equipment, determines the directorynumber of the second user equipment to which the call is directed,interrogates the list with the directory number of the call setuprequest to determine if a directory number of the list matches thedirectory number of the second user equipment, performs an evaluation ofwhether the second user equipment is authorized to access the femtocellsystem by evaluating whether the directory number is assigned to thesecond user equipment that is authorized to access the femtocell system,and by evaluating whether the second user equipment is currentlyoperating in a service area of the femtocell system, and completes thecall setup based on results of the evaluation.
 17. The system of claim16, wherein the femtocell system determines an electronic serial numberof the second user equipment.
 18. The system of claim 17, wherein thefemtocell system interrogates the list with the directory number, readsthe electronic serial number from the list, and wherein the electronicserial number is associated with the directory number.
 19. The system ofclaim 16, wherein the femtocell system determines the second userequipment is authorized to access the femtocell system.
 20. The systemof claim 19, wherein the femtocell system determines the second userequipment is registered with one of the femtocell system and a femtocellnetwork that includes the femtocell system, and completes the call setupwith one of the femtocell system and a femtocell network that includesthe femtocell system, and wherein no call setup singling is transmittedoutside the at least one femtocell system and the femtocell network.